Reaching for Pluto: NASA Launches Probe to Solar System's Edge

NASA's New Horizons spacecraft launches into space on a mission to the planet Pluto and beyond on Jan. 19, 2006.

Credit: NASA.

This
story was updated at 5:09 p.m. EST.

NASA's
first probe bound for the planet Pluto and beyond rocketed toward the distant
world Thursday after two days of delay due to weather.

A Lockheed
Martin-built Atlas 5 rocket flung the New
Horizons spacecraft spaceward at 2:00 p.m. EST (1900), sending the probe
speeding away from Earth at about 36,250 miles per hour (58,338 kilometers per hour)- the fastest ever for
a NASA mission. The probe should pass the Moon at 11:00 EST (0400 Jan. 20 GMT) on
a nine-year trek towards Pluto.

"The
United States has a spacecraft on its way to Pluto, the Kuiper
Belt and on to the stars," said New Horizons principal investigator Alan Stern
during a post-launch press conference. "I have July 14, 2015 emblazoned on
my calendar."

Initial
reports indicate that the probe is in good health. Grounds stations received their
first signals from New Horizons at about 2:50 p.m. EST (1950 GMT), which showed
the spacecraft's radioisotope
thermoelectric generator (RTG) - which uses heat from decaying plutonium
dioxide to generate power - is online and performing as expected, mission
managers said.

"The
vehicle looks to be right where it needs to be," NASA launch manager Omar
Baez, said just after liftoff. "It was Mother Nature that was holding us
back earlier, but we got through it."

Weather
woes

Indeed,
nature was the bane of New Horizons' launch from the beginning.

Flight
controllers were forced to scrub
an initial Jan. 17 launch attempt when winds proved too strong at the
spacecraft's Complex 41 launch pad at Cape Canaveral Air Force Station in Cape
Canaveral, Florida. One day later, severe storms in Maryland prevented
a second launch attempt when they knocked out power at New Horizons' mission
control center at Johns Hopkins University's Applied Physics Laboratory. The
laboratory is managing the mission for NASA.

"It was
suspenseful, there was no question," Stern said of today's countdown, holding
up a small stub of a pencil. "This has been our mascot for years, this little
ground-down pencil...it represents perseverance."

New
Horizons mission managers took today's launch as an opportunity to honor Pluto's
past.

Riding
aboard the NASA spacecraft are ashes of the late astronomer Clyde
Tombaugh, who discovered
the planet in 1930 at the Lowell Observatory in Flagstaff, Arizona. Tombaugh
died in Jan. 17, 1997, nine years to the day of New Horizons first launch
attempt this week.

"I
want to point out what a great honor it is to have Clyde's widow [and family]
here with us," Stern said of Patsy Tombaugh, her daughter Annette and
son-in-law.

Jim
Kennedy, NASA's Kennedy Space Center director, said earlier this week that a Florida
quarter - bearing the image of a space shuttle - is also accompanying the
probe to Pluto.

Onward
to Pluto

The $700
million New Horizons mission began in earnest as the probe popped free from its
third stage to begin the long, nine-year trek toward Pluto. The spacecraft
should swing past Jupiter, grabbing a gravity boost in the process, in late
February 2007, NASA officials said.

"This
mission is going to the far frontier of our solar system," said Richard Binzel,
a science team co-investigator from the Massachusetts Institute of Technology (MIT),
before today's launch. "In some ways, our basic knowledge about Pluto could fit
on a three-by-five inch note card."

Pluto is
the only member of the traditional nine-planet solar system not visited by a
spacecraft, a statistic New Horizons hopes to change. The probe carries seven
primary instruments to study Pluto, its moon Charon
and two
other objects - currently dubbed P1 and P2 - discovered orbiting the planet
last year.

The
spacecraft is designed to begin observing Pluto about five months before its
scheduled flyby in July 2015, which will take place about three billion miles
(five billion kilometers) from Earth on the 50th anniversary of Mariner
4's flyby of Mars - NASA's first ever red planet flyby, Stern said.

Mission
managers expect New Horizons to speed past the planet at about 31,000 miles per
hour while using its instrument package to build detailed maps of the planet,
as well as study its composition and tenuous atmosphere.

About nine
months after the encounter, the 1,054-pound (478-kilogram) spacecraft should finish
sending its Pluto observations to Earth, which will take about 4.5 hours to
reach researchers on the ground.

The
information New Horizons will send to Earth about Pluto and its moons will
likely alter our view of the distant, icy world, researchers said.

"I think it's
exciting that all the textbooks will have to be rewritten," Stern said.

Thursday's
space shot marked the second Atlas 5
launch for NASA - the Mars Reconnaissance
Orbiter flight was the first -
and the seventh flight overall for the Lockheed Martin rocket. The launch also
marked the second success for NASA this week.

""This
week, NASA has accomplished an amazing one-two punch for...exploration," said Andrew
Dantzler, director of the solar system division at NASA's Washington, D.C.
headquarters. "It's been a great day."

Tariq joined Purch's Space.com team in 2001 as a staff writer, and later editor, covering human spaceflight, exploration and space science. He became Space.com's Managing Editor in 2009. Before joining Space.com, Tariq was a staff reporter for The Los Angeles Times. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. To see his latest project, you can follow Tariq on Google+, Twitter and on Facebook.